Epicyclic ball transmission



Nv. l2, 1929, G. s. MoRlsoN EAPICYCLIC BALL TRANSMISSION Filed-'July -231.926 2 Sheets-Shea?l INVENTOR "Elfi L! w, m A

WTNESSE-S INVENTOR Nov. l2, 1929. G. s. MoRlsoN EPICYCLIG ALLTRANSMISSION Filed July 23. 1926 wlTNsssEs M11/Mace .W. El. Y .M4N El..

.Patented Nov. 12, 1929 GEORGE SMITH -MORISON, 0F PTTSBURGfI-I,

INCORPORATED,OF PTTSBRGH, ENNSYLVANIA, A CORPORATION 0F `DETJIYTAIRLnrIoYcLicY YBarni TRANSMISSION Application sied July 23,

This invention relates to power transmis` sions, more particularly togearless transmission systems for effecting a reduction of speeds in apair of cooperatively rotating machine elements.

t is among the objects of this invention to provide a speed reductiontransmission embodying a plurality of rollerV transmittingmechanismsthat are associated'withia driving and a driven Velement andare adapted to cooperate through an eccentrically rotatable race-waywhich acts upon the rollers of one of the transmission members to effecta radial thrust o-f the rollers against a fulcrum inemberl having acorrugated face thereby producing a `relatively great reduction in thespeeds of the driving and driven elements.

Another ob] ect vide a speed reduction transmission of simle and compactmechanical construction which shall be positive in itstransmission ofpower between a driving and a driven element and which shall be ofrelatively high efficiency for the reduction in speeds edected incomparison with gear transmitting mechanisms of like capacity' and foreffecting similar reductions of speeds. Y Another object of thisinvention is to provide a speed reduction mechanism of the abovedesignated embodied in a housing member to constitute a self-containedunitary member that is readily applicablefor use to a substantialreduction in the respective speeds'l of a driving and a driven shaft andin which the housing and transmission mechanism is'.

' ment between the driving and driven elements of balls of differentcomprises a plurality, diameters forming a wedge between the drivingshaft and an eccentrically movable ring having a concentric vrace-way,the balls being retained in a'cage member which is secured of thisinvention is to p roV corrug'ations of the Vstationary fulcrum mem-r'ber to effect a driving ofthe roller-carrying.jl

character which shall `be V ball-retaining memberf large variety ofVapparatus in which it is desired to effect a" 1926. Serial No. 124,352.

rnnnsYLvANrA, Assiern'on` To Monison tol or formed'integrally with thedriven `shaft and adapted torotate therewith. In that transmissionmechanism an i eccentrically movable ring is restrained 'against rotary'movement7 constituting theballretaining cage a planetary member andproviding a' speed reduction between the driving and driven ele Y mentswhich is increased byl 1 above the ratio V determined by the differencein the diameters Y of the balls and ball race inside the eccentric ringand ofthe driving shaft with which the balls are engaged. A, v y

In one formiof the present invention the ball transmission is utilizedin substantially the same manner as described in the` above mentionedapplication withl the exception that the eccentrically movable ring isnot positively restrainedy against movement.r The,

eccentricmovement ofthe ring isherein utilized to produce an vepicyolicor progressive thrust movement with respect to an encircling l fulcrummember .thereby pushing or rolling,-`v

a plurality of circular rolling members asso- Y ciated with a secondAcage memberinto the"` cage and consequently a relatively great reductionof speed between the driving and the ll 'driveny shaft, the latter beingrotatablyl secured or formed integrally withthe cage or lAn advantage ofthe Y constituting a preferred form of the present transmission devicefk invention resides in an improvement in the manner of holding theballs of the .inner transmission in angular Aspaced relation and` ofyieldingly urging one'of the ballmembers into the wedge-space formedbythe eccentric disposition of the outer race with respect*i .f to theinner driving shaft, the mounting of the balls beingrsuch that thedevice may be operated in either direction of rotation., i c The Outerball transmission Vemployed `in the instant Vcase functions somewhaton the principle of a wabble gear, which is an eccentricallyl movablegear cooperatively. ken-r gaged with an internal gear and having ka,Y

difference in tooth ratio `determined bythe reduction in speed it isdesired to obtain. One of the objectsofusing the'ball trans-` kicamission is to obtain smoothness of operationv 4to eliminate soundproduced by resonance set the specific rollers illustrated.

f In the accompanying drawing Vconstitut-- ing a part hereof, and inwhich lilrereference characters Vdesignate like parts, Fig. 1 is avertical sectional view partially in `elevation of a speed reductiontransmission embodying the principles'of this invention; Fig. 2 is anlfendelevational view thereof taken along the a:

lines 11%1'1, F 1;; and-Figs. 3 and 4 are l' respectivelyavertical'sectional and. end elevational'viewof a modified formoftheinvention in which the drive shaft is provided with an eccentric to takethe placeof the in@ ner ball transmissions.` l Y Y Referring to theseveral figures of the drawing, the structure thereinillustratedcomprises a housing member 1 having a projecting end portion2provided with a central Y opening 3 for receiving a journal bearing4.

An Vend bracket 5 is secured tothe open endV ofthe housing bysuit'ablebolts 6. A pluralityv of shafts '7. and 8 comprising respectively adriving anda driven shaft are journalled for rotation vin coaxialalignment within the housing inthe following manner. The shaft 8whichisprovidedwith a flange 9 is journalled inthe bushing 4 inthe housingmember; The shaft 8 is vprovidedfwith a recess 10 i having a ballbearing `11 secured therein for journalling the extended end'12 of thedrive shaft 7.

'lhe flange 9 of the shaft 8 is'rprovided with -an offset portion 13adapted toV seat a cage extending member 14 having an axiallyf 16, Fig.2,

flange 15 provided with recesses for. receiving a plurality ofA balls17.V An orbital or fulcrum member 18 comprising a ringhaving acorrugated inner face 19 is secured in the housing member in alignmentwith the rollers 17 of the member 14.

The corrugations of the fulcrummember 1 8 are'bounded by arcsof equalcircles the radii Gaf ` of which are respectively equal tothe diame--ters of the rollers 17 with which they are eiigaged. t

An'inner cage comprising, a pair of discs M2O and 21. constitutingvfloating members around the shaft 7 and secured in spaced relationbyvrods or rivets 22,fis 'provided with bearing pads 23 having suitableseating dev t pressionsV for securing balls or rollers 24.

lT hecage memberV is further provided with a stop member 25 ofVsubstantial V-shape, Fig.

or rollers 2, and a` plurality of hexagonallyshaped bearing pads 26 thatare freely movable within the cage. Ball or roller members 27 areinserted between oppositely disposed pads 26 and the latten are adaptedto engage the divergingfaces of the stop 25.` A spring 28 is secured bya cover plate 29 yto the stop 25,

as shown, and is formed to engage-the hex# agonal facesof the pads 6 toyieldingly urge the latter away from the sides of the member 25, so asto insure the'balls 27 being held in gripping position in thetransmission. The roller members 24 and' 27 are of different sizes,consequently the ring 31 has an eccen-l tric disposition with respect tothe shaft 7, the cage member 15 and the fulcrnm member 18, all of whichare concentric'. The ring 31 is free to rotate in either direction.

The operation of this roller transmission speed reduction mechanism* isbriefly as fol lows :'The inner shaft 7 is coupled to a suitableprimemover or driving member through which it is actuated to revolve therollers 24 and 27of'theinner transmission, and the latter by virtue ofthe spring 28'are forced into l the' converging space between thesurfaces of the shaft 7 and of the inside of eccentric ring 31. @ne orthe other ofthe roller members 27 is urged into the narrowing spacebetween the shaft and ring members by the spring member 28, dependingupon the direction-of rotation of the shaft 7. This wedging effectproduces a positive trans-` mission of power from the ldrivefshaft 7`through the 'rollers 24 and 27 to the eccen-V tric ring 31 Ywhich issubjected to an epicyclic movement with respect to thecorrugatedfulcrummember 18. j The roller mem- A bers 17 by virtue of theirengagement with the onter face of theV eccentric ring31Y are'V iceprogressively vpushed into the corrugations of the member 18 causingthem to rotateI about axes parallel; to the axis ofthe'driveA shaft 7therebyadvancing the rollers in the" direction oppositev the directionof rotation:V G

of the drive'fshaft 7. The cage member14 carrying therollers 17 beingsecured orvr formed integrallyuwith' the driven shaft '8Y iscarried bythe rollers in the direction' of# theirtravel onl the corrugated pathofmem-` ber 18. The rollers' constituterthe medium by which power orrotary movement is trans?l mitted from the'drive shaft'7to the drivenshaft 8. The epicyclic movement of the ring j Y V31 effects aprogressive successive radial thrust of the severalrollers 17 againstthe f corrugated faceof the outer member 18 and this effects a `forwardvrolling move-v ment of the members 17 ,which carry cage 14, so thattheeifect is to slowly rotate the cage 14 carryingthe rollers. y The numberof rollerscarried by the cage member 14 .is always less than vthe numberj of 4depressions or corrugations in the fulcrum 18 and normally oneless. In the illustradriving members.

tion there are twelve corrugations in the ful? crum member 18 and elevenrollers carried by the cage memberl, Which provides a tvvelveto-onereduction in the speed of the driven shaft 8 as compared `to the numberof individual complete thrusts of the eccentric 31 upon any one of therollers 17. Since the eccentric movement and consequent radial thrust ofthe ring 31 is effectedv through the -unequally sized rollers 24:' and27 revolving about the driven shaft,fand sinceV this arrangement itselfproduces val reduction in speed as `between rotations of tlie'driveshaft and eccentric thrusts of the ring onany one radius line, there isan additional reduction Y of speed depending upon thediniension of theshaft 7, rollers 24 and-27, and the diameter of the inner face of thering 31.

The reduction in speed between shafts 7 and 8 is therefore dependentupon the length of radial thrust of the eccentric, the size of the balls17 and number of corrugations in track 18, as Well as the elementsinside the eccentric ring. By varying these elements vWithin thepossible ranges, a wide-variation in speed ratiobetweeii drive anddriven shaft is possible. For any one device however the speed ratio isconstant. The smaller the throiv of the eccentric the greater thespeedreductionis in a given diameter offulcruni ring. v c Y In themodification shown in Figs. 3 and 4, aneccentric 40 is mounted on orformed integrally with, theshaft 7 and is adapted to -g rotatetherewith. The eccentric l0 functions to produce an'epicyclicA movementfor thrusting Vtlierollers 17 against the corrugated path-of the member18 and cpnsequently rolling them thereon. However, it is necessary inthis construction to provide a ball bearing 4:1 the outer ring member ofwhich is floatiiigly free to revolve as isthe ring 31 in Figs. 1 and2,.and for the same'reasons. The utilization of an `eccentricsuch as thejme'mber 40 `in place of the inner ball transmission shorvn in Figs.land 2 produces less reduction in the speed 'of thedriven shaft, but

makes a'sinipler and cheaper construction.

A. speed reduction transmission mechanism as described provides a; greatreduction of speed ina relatively small and compact unit as comparedwith other speed reduction units utilizing planetary and Wabble gears,and it provides relatively smooth and silent opera-v tion, with arelatively small amount of friction, due tothe use of rolling contactsof The apparatus may be used to speed up as Well as'to reduce relativerotation by driving shaft 8; Shaft v 7 then becomes the driven shaftandwill be given very great speed multiplication.

t Will be obvious to those skilled in the- Y,art that variousmodifications may be made 'in the details vcoiistraction and in the sizeapertures provided therein, roller members mountedy in the apertures ofVsaid cage and adapted' for engagement With said race,'and a fixedcorrugated fulcrum and proportions of the several"cooperating` partsWithout departing from the principles herein set forth. Y I

I claim: 7

1. A transmission device comprising in combination, a pair of coaXiallyaligned,-

shafts, rollers disposed around one of said shafts in angnilar4spacedrelation, tivo of said rollers having unequal diameters, a free`roller race disposed around'and contacting` With said rollers, a cagemember secured to rotate With the other of said shafts having rollershaving unequal diameters, a free roller race disposed around andcontacting "with said rollers, a cage member secured to rotate with theother of said shafts having apertures provided therein, a'pluralityofroller members mounted in the apertures of said cage and adapted Jforengagement With said race, and a lined corrugated fulcrum memberdisposed around and contacting with said last named rollers, thecorrugations of.` said v' bounded by arcs of v fulcrum member beingequal circles the radiiv of Which are respectively equal to thediameters ofthe rollers with Which they are engaged.

3. A transmission :device comprising in Vcombination,` a pair ofcoaxially aligned' shafts, rollers disposed around' one of said tvvooffsaid rollers having'unequaldiaineters, aifree f shafts inangular spacedrelation,v

rollerirace V.disposed around and contacting with said rollers, a, cagemember secured to f.

rotate with the other vof saidY shafts having a lplurality of memberdisposed around and contacting Y- with said last'iiamed rollers, saidshafts, cage and corrugated fulcrum members being concentri-c toeachother and said rollerirace` be-4 ing adapted forsimultaneousreccentric rotating revolving thereto.

shafts in angular spaced relation,r tvvo of said rollers having unequaldiameters, a free rollerrace disposed around andcontacting with saidrollers, a cage member secured to rotate with the other of saidshaftshaving apertures provided therein, a 'plurality of rollery membersmounted in the apertures of gyrating movement relative i' n Y v ;v Y su,4. A transmission *device comprisingr "in combination, a pair ofcoaXiallyV aligned shafts, rollers Vdisposed around vone of said saidcage and adapted Yfor engagement withV said race, and a stationarycorrugated fulcrum member disposed around and contacting with said lastnamed rollers, said last named rollers being adapted for angularmovement on the path of the corrugated member. 'n i '5. A transmissiondevice' comprising in combination, a pair of coaxially aligned shafts,rollers ldisposed around one of said shafts in angular spaced relation,two of said rollers having unequal diameters, a free roller racedisposed around and contacting with said rollers, a cage member securedto rotate with the other of said shafts having aper-k tures providedtherein, azplurality of roller members mounted in theV apertures of saidcage and adapted for engagement'with said race, and a fixed corrugatedfulcrum member disposed around and contacting with said last namedrollers, said rst named rollers constituting wedge membersv betweentheir cooperating shaftand said race, and said last named rollers beingadapted for radial displacement into and out ofthe corrugations of saidfulcrum member.

Q6. A transmissionv device comprising in combination, a pair ofcoaxiallyaligned shafts, rollers ,disposed around one of said shafts inangular spaced relation, two of said rollers havingV unequal diameters,a free roller race disposed around and contacting with said rollers, acage member secured to rotatewith'the other of said shafts having apvertures provided therein,a plurality of roller members mounted in theapertures of said Y cage and adapted for engagement with said race,andra fixed corrugated fulcrum member disposed around and contactingVwith 'saidlast named rollers, said `roller race being Vadapted to. wedgesaid firstvnamed 'rollers with their cooperating shaft and toprogressively push said last named rollers into the corrugations of saidfulcrum member, whereby to drive the cage. v

l,7. 'A Ytransmission Vdevice comprising in combination, a pair ofooaxially` yaligned shafts, rollers disposedaround one of said shafts inangular spaced relation, two of-said rollers having unequal diameters, afree roller race disposed around and contacting withk said rollers,acage member secured to rotate with. the other. of said shafts havingaperturesprovided therein, a plurality of roller mem- Y bers mounted inthe apertures of said cage and adapted for engagement with said race,and a xed corrugatedv fulcrum member disposed around and contacting withsaid' last named rollers, said first named rollers being adapted toproduce a wedge effect between v their cooperating shaft and saidlroller race, and saidlast named rollers being of uniform diameter andfreely disposedin the apertures of said cage member.

8. A transmission device comprising in combination, a `pair of coaxiallyalignedV shafts, rollers disposed around one ofsaid' shafts in angularspaced relation, two of said rollers having unequal diameters, a freeroller race disposed around and contactingVV with said rollers, a cagemember secured toV rotate with the other of said shafts having aperturesprovidedV therein, a plurality of Y roller members mounted in theapertures of said cage. and adapted for engagement -with said race, anda fixed lcorrugated fulcrum member disposed around and contacting withsaid last named rollers, said first named rollersbeing adapted tovsubject the roller race to an epicyelic movement wherebythe latterprogressively and successivelypushes said last named rollers into vthecorrugations axial alignment, an inner and an outer cagek memberassociated with said shafts, rollers disposed in said' cage members, aring provided with an inner and an outer race sepa-J rating the rollersof said'inner and outer 'cage members, and a fixed fulcrum member hav-king a corrugated path for engaging the rollers of said outer cagemember, two of the rollers of said inner cage having different diam'-eters whereby to c'onstitutesaid ring an ec- Vcentrically rotatablemember whereby to produce a radial androlling motion of the ro1l,

ers o f said outer cage to effect their engagement with the corrugatedface'of said fixed fulcrum member.

l0. A transmission device comprising in shafts in angular spacedrelation, two of said rollers having unequal diameters,v a' roller racedisposed around and contacting with said rollers, a cage member securedto rotate cage and adapted for engagement with said race, and acorrugated fulcrum'vmember'disposed around and contacting with said lastnamed rollers, the corrugations of said fulcrum member being bounded byarcsuof equal circles the radii of which are respectively equal to thediameters of the rollers with which they are engaged, said corrugations'being greater in number than theV number of cooperating rollers.

Y 11. A transmission device comprising a r`o" tary shaft having a fixedaxis, a plurality ofV Vrollers mounted on the shaft and adapted'torevolve freelythereabout, two of'said rollers having differentdiameters, a ring eccentric to the shaft surrounding andbearing on saidrollers, said ring being free to rotate on its axis and simultaneouslyto move in a path determined by revolution of its axis about they axisof the shaft, a rotatable cage coaxialV combination, a pair Vof'coaxially aligned shafts, rollers disposed around one of said' with theshaft, rollers carried n the cageV

